Hadith 1423
It is narrated from Hisham bin Urwah that Sayyiduna Abdullah bin Zubair (may Allah be pleased with him) used to pass judgment based on the testimony of boys regarding their mutual fighting.
Hadith 1423B1
قَالَ مَالِك : الْأَمْرُ الْمُجْتَمَعُ عَلَيْهِ عِنْدَنَا، أَنَّ شَهَادَةَ الصِّبْيَانِ تَجُوزُ فِيمَا بَيْنَهُمْ مِنَ الْجِرَاحِ، وَلَا تَجُوزُ عَلَى غَيْرِهِمْ، وَإِنَّمَا تَجُوزُ شَهَادَتُهُمْ فِيمَا بَيْنَهُمْ مِنَ الْجِرَاحِ وَحْدَهَا لَا تَجُوزُ فِي غَيْرِ ذَلِكَ إِذَا كَانَ ذَلِكَ قَبْلَ أَنْ يَتَفَرَّقُوا أَوْ يُخَبَّبُوا أَوْ يُعَلَّمُوا، فَإِنِ افْتَرَقُوا فَلَا شَهَادَةَ لَهُمْ إِلَّا أَنْ يَكُونُوا قَدْ أَشْهَدُوا الْعُدُولَ عَلَى شَهَادَتِهِمْ قَبْلَ أَنْ يَفْتَرِقُوا
Imam Malik, may Allah have mercy on him, said that if boys fight and injure each other, their testimony is valid, but the testimony of boys is not valid in other cases and lawsuits. This is also valid only if, after fighting, they did not separate but remained together. If they went their separate ways, then their testimony is not valid, unless they made just people witnesses to their testimony.